This patch adds a routine to protocol.c that correctly transfers data to
or from a scatter-gather buffer.  According to Jens Axboe, we've been
using page_address() incorrectly -- it's necessary to use kmap() instead
-- and in fact it doesn't give the desired result when the buffers are
located in high memory.  This could affect anyone using a system with 1 GB
or more of RAM, and one user has already reported such a problem (as you
know).

The three fixup routines in protocol.c and usb.c have been changed to use
the new s-g access routine.  When similar adjustments have been made to
all the subdrivers, we will be able to eliminate the raw_bulk.c source
file entirely.